Challenges and Prospects of Vehicle OTA Spherical Near-Field Measurement Probes

This Paper Discusses the Issue of Measuring Probe Indicators for Large-Scale Equipment, Such as Automobiles, under Conditions of Offset Configuration. a Simulation of Spherical Near-Field Measurement based on an Offset Configuration is Presented in This Paper. the Measurement Error is Defined According to the Reference Data Calculated by Spherical Wave Expansion Theory. through Comparative Analysis of the Simulation Results, the Main Reason for the Measurement Error is the Insufficient Coverage of the Probe\u27s Beamwidth. by Adjusting the Probe\u27s Radiation Pattern using Simulation Software, an Optimized Probe that Satisfies Near-Field Measurement Requirements under Meter-Level Offset Conditions is Obtained. Finally, based on the Simulation Results, a Set of Recommended Values for the Main Performance of the Optimized Probe is Provided

INFLUENCING FACTOR ANALYSIS OF FATIGUE CRACK INITIATION LIFE ON CRANE LATTICE BOOM

The crane lattice boom is complex and the load is diversity,part of the structure may suffer plastic deformation because of the high stress concentration or poor weld quality under exceptional poor load conditions. So using strain analysis parameter is reasonable compared to stress parameter. The paper was focused on the fatigue crack initiation stage of crane lattice boom. The method of local stress strain was used combined with the correction Neuber method. A crane fatigue crack initiation life evaluation algorithm model was built. According to the model,three main factors which will influence the initiation life calculation were analyzed and compared. Fatigue tests were also carried out with K nodes of crane lattice boom. When the material was determined under certain circumstances,the stress concentration factor had the most impact result on the life. The mean stress on the material had the less impact but it cannot be ignored. According to the Factors,optimization suggestions to lattice boom spatial structure and work process improvement measures were proposed

A 2-Element K-Band Series-Fed Directional Antenna Array for Millimeter Wave Radar Applications

In this paper, a K-band series-fed directional antenna array based on a wide bandwidth, high-efficiency electromagnetic radiation structure is proposed for millimeter wave radar applications. Only two fundamental elements are needed to meet design specifications. By cutting off one side of the original antennas and using the grounded coplanar waveguide (CPWG) and microstrip hybrid feeding method, a series-fed structure is innovatively developed to make the designed array simple in structure and efficient in space utilization. Simultaneously, the feed structure of the CPWG and the through-hole vias around the antenna are proposed in combination to form a semi-closed shielded cavity structure. It can better constrain the electric field, suppress radiation from the transmission line, alleviate the antenna radiation pattern distortion and reduce the transmission line loss. The similar beamwidth is mainly achieved in both the E- and H -planes by placing the two elements vertically perpendicular to the H-plane. The measured relative bandwidth of the antenna array is 24%. Within the designed bandwidth (22-28 GHz), the measured |S11| is lower than −10 dB, and the gain is basically above 10 dBi. The measured E- and H-plane beamwidths are close to each other with a difference of less than 10°for each frequency, while the beamwidth value varies between 32°and 51°in the entire frequency band of 22 to 28 GHz. The simulated results are in good agreement with the measured ones

STUDY ON SAFETY OF T PLATE CONTAINING CRACK BASED ON BS7910

Failure assessment diagram（ FAD） is usually used to evaluate the safety of welded structures containing cracks.There are three assessment levels in BS7910. As the assessment level increases,accuracy is improved and more data is required.This standard is widely used in safety assessment of pressure vessels and pipelines. The working level of offshore crane is relatively high and fatigue cracks can be found on it during the routine inspection. However,due to its high cost and long cycle of maintenance,the productivity is seriously affected. Therefore it is vital to commence safety evaluation on the cracked structure. This paper utilized Shao Yongbo’s experimental data to establish the 3C curves of the cracked structure of offshore crane,and compared it with the 2A curves of the BS7910 standard. The result shows that the tendencies of both curves are the same and 2A curve is more conservative. Thus the structure can be evaluated according to BS7910. This paper offers the critical load of T-plate that contains certain dimension of crack according to level 2A evaluation

DC Ground Compact Wideband Omnidirectional Vertically Polarised Slot Loop Antenna for 4G Long-Term Evolution Applications

A compact, wideband, omnidirectional, vertically polarised antenna without electrostatic discharge problems is proposed in this study for 4G long-term evolution applications. The proposed antenna is composed of three identical basic radiators separated by an angle of 120°. The basic radiator is based on a slot loop which is a wideband and DC ground structure. By bending the basic radiators, the antenna achieves better impedance matching and lower gain variation in the horizontal plane in a compact size. The proposed antenna reaches a fractional bandwidth of 45.5% for the voltage standing wave ratio (VSWR) \u3c 1.5, a peak gain from 2.4 to 3.8 dBi with a gain ripple around 2 dB in the omnidirectional plane. It operates from 1700 to 2700 MHz, covering most 4G long-term evolution frequency bands. Both simulation and measurement of a prototype is done in this study to verify the antenna performance